The weather situation on 14 November 2002 was characterized by a south-westerly flow and by the passage of a cold front over Switzerland during the day, which was related to a low pressure system centered over the British Isles.
Warm and moist air from the Mediterranean was transported from the south towards Switzerland and the intense precipitation that occurred over the western border of Switzerland that day resulted from the slowly moving cold front and the lifting of the warm and moist air above the southern part of the Jura mountains. Both the topography and the passing cold front were responsible for the lifting of the air mass.